Alonzo hitchcock



2 Sheets-Sheet 1.

(No Model.)

A. HITCHCOCK..

DRAPTSMAN'S J2-SQUARE.

No. 274,194. Patented Ma.1.20,1883.

lrwem: We Hinke JR Messes.'

Yy www UNITED STATES PATENT QEEICE. V

ALONZO'HITCHGOGK, OF NEW YORK, N. Y.

DRAFTSNIANS T- SQUARE.

SPECIFICATION forming part of Letters .Patent No. 274,194, dated March 20, 1883. y

Application filed May 6. 1882; (Nov model.)

To all whom it may concern Y v Beit known that I, ALONZO HITCHCOCK, of the city, county, and State of New York, have invented certain new and useful Improvements in Draftsmens T- Squares; and I do hereby declare that the following isa full,clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, making a part of this specification.

r My invention relates to improvements in the construction of draftsmens T- squares.

The object of my invention is to furnish a suitable head for a T-square which shall be independent ot' the blade, and to which any one of a set of separate blades maybe readily attached and be adjusted to any angle.

It consists of a straightedged metallic plate,

adapted either to constitute in itself 'a head for a T-square or to be secured to an ordinary wooden T-head, `and which is formed with anh offset or lip projecting from and beyond its,

straight edge, midway of its length,.to rest upon the face of the drawingboard as a sup- C port for the head, the width of said oii'set or" y lip being equal to or less than that of the blade of the square, so asto permit the head to be tipped in either direction when required, and which is likewise provided with a iiange or shoulder along the under side of its straight edge, to serve as a guide for the head against the edge of the drawing-board, said iiange being formed continuously in one piece with the head along its entire length, or at intervals in the ferm of lugs, or otherwise secured by the attachment of the metallic head to a wooden head whose inner straight edge,coin ciding with that of the metallic head,`shall constitute its guiding-lian ge. This part of my invention enables me to furnish at a low cost -a correct and exact T-head, adapted for use in and of itself as an independent head, or which may be combined with a simple straight wooden head to produce cheaply a long head for the square, where such is preferred.

It consists, secondly, in uniting the blade of the square to the separate metallic head-plate by means of an interposed separate `metallic connecting-'plate adapted to be pivoted to the metallic head and rigidly,7 secured to the blade,

and which finds support upon the central lip projecting from the straight edge ofthe head.-

This part of my invention supplies, in connection `with the independent metallic T-head, a ready andinexpensive method ot' unitingthereto any suitable blade, and permits of an interchange of blades of dierent lengths with the same head, and of its adjustment to any required angle, as may be desired.

ln the accompanying drawings, Figure 1 is a plan view of my improved independent head constructed to form in itself a complete head for the T- square, and Fig. 2 a central transverse section thereof in linetvxot' Figi. Fig. 3 is a plan view of the under side of the connecting-plate when attached to the blade of the square, and` Fig. 4 a transverse section thereof in line y y of Fig. 3. Fig. 5 is a plan* view of my improved head when constructed in simplest cheapest form for attachment to a wooden T-` head, showin it so attached, Figs. 6 and 7 being similar views of modifications thereof', (the latter heilig drawn upon a reduced scale to embrace the whole length of the T-head;) and Fig. 8, a section in line z zot' Fig. 5, illustrating a special form of socket for the end of theclamping-screw. Fig. 9 is a plan view of the under side ot' the connectingplate, adapted for use with thehead shown in Fig. 5, and its modifications. Fig.. 10 is a plan view of a metallic T- head, with the connectin g-plate carrying the blade secured in place thereon t0 constitute a complete T-square, Fig. 11 being a central section thereot in line w zo of Fig. V10, showing its application to a drawing-board. Fig. 12 is a sectional view of the independent head, Fig. 5, when secured upon a wooden Thead, with the connectingplate carrying the blade secured in place thereon, making acomplete T- square. Fig. 13 illustrates an independent T-head when constructed in extended form for large work. Fig. 14 is a section in line t t ot' Fig. 13, illustratin g the application of that form of head to a drawing-board, the blade-plate being omitted. Fig. 15 is a plan` view ci' a detachable metallic head for a wooden T-head constructed without a projecting flange.

A is a metallic head-plate for a T-square, which may be cast in light ornamental form,

with the necessary straight edge a. Fromthe center ot' this straight edge can offset or lip, B,

ofa. width not exceeding that of the blade of the T-square, is formed to extend at a right angle With said edge in a plane parallel to that ot' the plate, so that it may afford a bearing for the head upon the face of the drawing-board when the straight edge a. is brought in line with the edge of the board. lVhen the headplate is designed to serve in itself as the head of the.Tsquare,-a flange or shoulder, C, (see Fig. 14,) is formed to project along the under side of its straight edge a, for the purpose of bearing against the edge of the drawingboard, over and upon which the lip B projects and rests. Instead ot' making said ange continuous along theentire lengt-h of the edge a, Fig. 14, two or morelngs may be substituted therefor to perform the same function. When the head-plate is designed for use in combination with a wooden T-head (see Figs. 5, 6, and 7) the flange (l may be omitted, the edge of the wooden head furnishing in such case the required bearing against the drawing-board.

The connection ot' the blade P with the head A of the T-square is effected by means of a 4metallic connecting-plate,D, adapted to be secured at one end to the blade, so as to form, in effect, an extension thereof, andto rest and rotate at the other upon the face`ot' the headplate, to which it is pivoted. The pivotal connection is formed by means ot' a pivot-pin projecting from the one to pass through a pivothole in the other, (in which' case a nut is let onto the end of the pivot-pin to clamp the two together when properly adjusted,) or, as illustrated in the drawings, by means ot an annular groove, m, formed in the face (or in an o'- set from the face) of the plate D, to receive a counterpart annular projection, n, upon the face of the head A,the projection aand groove m being made to fit and interlock with great accuracy and to move upon each other with ease, so as to form a perfect annular pivotal joint, having such an extended bearing as'shall insure exactness and precision of adjustment and movement. The two plates A D, when thus pivoted or hinged together, are secured and at pleasure locked by means of a central clamp-screw, E, Figs. l0 and 11, whose head is fitted in a seat countersunk in the under side of the head-plate, and whose shank, extending up through the head-plate-at its pivotal center and through a corresponding aperture in the connecting-plate D, is fitted upon lts outer end with a thumb-nut, E. By screwing down this thumb-nut firmly upon the bladeplate the two plates will be bound together, and may thus be locked in any position.

The annular joint may be formed upon the 'projecting lip B of the head-plate, as shown in Flg. 1, or upon the body of the head, as shown in Fig. 5. In either case the pivotal centeris placed in the middle of the length of the head.

The outer free end of the connecting-plate D is preferably finished with a point, 7c, to sweep asan index over a scale laid o' upon the arc of a circle describedmfrom the center of the annular joint, so that it 'may serve to indicate the angle at which the connectingplate and its attached ruling-blade P isturned and fixed. In order-to more positively lock the blade at a right angle to the straight edgev of the head, a set-screw, F is fitted in the outer end of the connecting-plate D, to pass into a seat provided in the head-plate in position to receive the end of the screw when the lblade and head plate are exactly at right angles.

Byforming additional apertures for the end ot' the set-screw at different' determined points in the head plate, or by passing it through a slot and fitting it wi-th a nut, the same device maybe used to lock the blade at anyindicated angle.

The connection of the detachable head A with a wooden T-head, S, is simply made by@ screws ff, as shown in Figs. 5 and 6. and the detachable connecting-plate D is in like man*` ner readily secured to the blade by the screws ff, Figs. 3 and 10. The interlocking grooves m and projections n, which form the annular joint between the head-plate and detachable blade-plate, are all made to correspond, irrespective of' the forms and sizes of said-plates, so as to bein all cases interchangeable. By this means a set of blades ot' diterentvwidths or lengths 'may be used interchangeably with a single head; or the same blade may be fitted to different forms orleugths of heads. j

Where the head-plate is used in Acombination with a wooden head, as illustrated in Fig. 8, a metallic seat or socket, c', may be secured in the wooden head to receive and engage the end of aclamp-screw, G,Fig.12,made to screw down into it from the outer side of the bladeplate. t

My improved head may be ot various forms, as shown in Figs.1 and 10, 7 and 13, and when -designed for use with a wooden T-head may be reduced to very small dimensions,as shown in Figs. 5 and 6, so as to att'ord simply a seat for the annularjoint between it and the bladeplate.

I claim as my inventiony 1. Thecombination, with each other and wit the straight inner edge of the head of a T- square constructed independently of its ruling-blade, ot' a lip, B, of substantially the same width as the detached blade, projecting centrally from the straight edge, to provide a sup port for the head upon the face ot' the drawing-board, and a ange or'shoulder, C, projecting along said straight edge at right an gles to the lip, to afford a guide for the head against the edge ofthe board, substantially in the manner and for the purpose herein set forth.

2. The separate blade-connecting plate'D, in connection with Athe independent head A and a detachable blade, P, to connect the blade and head, substantially in the manner and for the purpose herein set forth.

3. The combination ofthe head A, straight I-oo edge a, flan ge or shoulder C, formedalong said In testimony whereof I have signed my name straghtedge, lip B, projecting centrally from to this specification in the presence of two subro the straght egge at rglhb angles to said danig; scribng Witnesses. l or shou der, etachab e connecting-p ate 5 5 pivoted to the head and resting upon the lip ALONZO HITCHCOCK' B, and blade P, secured to the plate D, all sub- Witnesses: stantially in the manner vand for the purpose JOHN A. ELLIS, herein set forth. FULLER WALKER. 

